This case-control investigation will be undertaken to determine the extent of increased risk of bladder tumors among past and present rubber workers in Akron from 1958 through 1972, and to determine the relationship of this risk to specific environmental exposures, with particular reference to aromatic amines and other suspect materials used in the rubber industry. Approximately 700 hospital diagnosed cases of bladder tumors in white males over 34 years of age will be matched on age, admission date, and hospital, with two sets of hospital controls. The percentage of rubber workers among cases will be compared to that among the controls. Smoking histories will be obtained on a sample of living cases and controls. Subsequently, detailed work histories will be obtained from company records on all rubber workers in the hospital case and control groups. Work histories will also be recorded on a third set of controls selected from the rubber companies' personnel files. Work histories will be grouped by production process categories and by specific exposure categories. Comparisons of specific exposures will then be made between these several rubber worker groups - cases and non-hospital controls, cases and hospital controls, and hospital and non-hospital controls.